At the WorldTour opener in Australia, Mark Renshaw of Team Dimension Data is racing with a new, adjustable aero stem from ENVE. In addition to a new sleek shape, the ENVE SES Aero Road Stem can adjust its angle and effective length.
The faceplate on the race bike’s stem had a glossy black finish Josh Evans/Immediate Media
Externally, the most obvious design feature is switching from the traditional four-bolt faceplate to a more streamlined design. Two bolts remain on the underside of the faceplate but up top, a larger, single bolt at a 45-degree angle secures the handlebars.
An integrated computer mount also works with lights and action cameras.
Two more traditional faceplate bolts are located on the underside of the stem Josh Evans/Immediate Media
As well as the updates to the layout of the faceplate bolts, the plate itself also sees a complete overhaul. Instead of a 180-degree vertical alignment of the plate, a curved plate with approximately 120-degrees of handlebar coverage creates a smooth and aerodynamic area at the most critical area of the stem in terms of aerodynamics. The actual stem body extends asymmetrically underneath the faceplate to ensure the handlebars are secured.
To the rear of the stem, the body narrows to a teardrop profile and both tensioning bolts are on a single side as opposed to the alternate side design of the current ENVE road stem.
But it’s what you can’t see that is the real story.
“The shape of the stem itself is aero, but the real aero benefit is how the shim on the steerer tube allows for adjustment of the stem angle,” ENVE’s marketing director Jake Pantone told BikeRadar. “The idea is that you can eliminate spacers; spacers aren’t aero.”
The shim can be rotated to effectively raise or lower the stem, from -7 to -17 angles. The shim design has been used by other brands, but usually not on high-end products like this.
A second 2.5mm shim adjusts for length, for a total of 5mm of fore/aft adjustment. This shim fixes the stem angle at -12.
Only one shim — either the angle adjust or the length adjust — can be used at a time.
Renshaw’s stem is maked up as 130mm, although professionals’ ENVE stems have been known to measure longer than commercially available models Josh Evans/Immediate Media
While fork steerer top caps are traditionally circular, the new ENVE stem has an oval top cap to accommodate the shim adjustments.
Pantone said he didn’t yet know the weight.
Click through the gallery above for a detailed look at the latest from ENVE on Renshaw’s machine.